Advances in semiconductor technology have brought electronic devices with continually higher operating speeds and a concomitant need for faster communication channels to transport data among these devices. Many technological advances and solutions have resulted from efforts to maximize the speed and quality of these communication channels as their increasing speeds have introduced new challenges. For example, higher frequencies increase the impact of the skin effect in physical conductors and dielectric losses in insulation material.
High-speed serial (HSS) links that convey a data signal from end to end using a wireline have grown in popularity as a worthwhile communications channel. The great variability in the physical composition and construction of individual wirelines, and other factors, have resulted in sophisticated transceiver circuits that can dynamically adapt to actual operating conditions, maximizing the rate at which data can be reliably received. The sophistication of these transceivers, however, generally requires a large amount of circuitry capable of occupying the entire area of an integrated circuit (IC) die. Accordingly, these solutions cannot be practically employed where high-speed serial communication is only ancillary to the principal purpose of the chip.
Moreover, multiple communication channels may be operated in tandem as a unified communication lane to support data transfer rates beyond the capability of a single channel. The increased data rates brought by coupling the data capacity of multiple channels brings with it the increased likelihood of signal cross coupling between the channels. Left unaddressed, this cross-coupled interfering noise reduces the potential maximum data rate at which each individual channel can receive data reliably. The problem with crosstalk from co-located transmitters at the receiver input takes on increasing significance as channel frequencies move from the sub gigahertz range to 6 GHz, 10 GHz, and beyond.
As a further complication, the move to higher and higher frequencies presents new signal reliability challenges to wireline (i.e., solid conductor) data transmission on wirelines measured in inches, or that may be wholly contained within the confines of a single IC die.